Cylindrical heat exchanger



Jan. 2, 1962 R. .1. MEIJER ETAL CYLINDRICAL HEAT EXCHANGER 2 Sheets-Sheet 1 Filed Dec. 4, 1958 I 11b 11 a INVENTOR ROELF JAN ME JER MAT TH AS LEONARDUS HERMA 5 Jan. 2, 1962 R. J. MEIJER ET AL 3,015,475

CYLINDRICAL HEAT EXCHANGER 7 Filed Dec. 4, 1958 2 Sheets-Sheet 2 INVENTORE:

POELF JAN ME JER MATTHIAS #EONARDUS HERMANS ,ywe

AGENT United States Patent Ofiic Fatented Jan. 2, 19%2 3,015,475 CYLINDRECAL lEAT EXCHANGER Roelf Fan Meijer and Matthias Leonardns Hermans, Eindhoven, Netherlands, assignors to North American Philips Company, Inc, Jew York, N. a corporation of Delaware Filed Dec. 4, 1953, Ser. No. 778,135 Claims priority, application Netherlands Dec. 5, 1957 5 tllaims. (Cl. 257-241) This invention relates to cylindrical heat exchangers containing spaces for the two media in heat exchanging contact which extend throughout the length of the exchangers. Known heat exchangers of this kind have a limitation in that t ey must be surrounded by insulating jackets which occupy a comparatively large amount of space so that the heat exchangers become comparatively bulky. In addition, the manufacture of a known heat exchanger made up from tubes takes much time since the tubes must be connected to the supply and discharge ducts for the media with a high degree of accuracy, and this operation requires much time especially if, with a view to the heat exchange aimed at, a construction is used in which the media are highly subdivided so that many tubes are required.

It is an object of the present invention to obviate these disadvantages. For this purpose, the heat exchanger in accordance with the invention is characterized in that it is built up from identical metal plates which are slightly spaced apart and are shaped so that in a cross section of the heat exchanger each plate comprises a central part which both at the end near the inner circumference md at the end near the outer circumference of the heat exchanger ends in at least one bent portion which runs into an edge part which extends according to the inner and outer circumference of the heat exchanger re spectively, so that at the inner and outer sides of the heat exchanger closed supply and discharge ducts for the media are produced by the portions and edges of adjacent plates, the media in the spaces between the central parts of the plates being in heat exchanging contact with each other through these plates, while the plates are connected together at or close to the end faces of the heat exchanger. The media can be liquid and/or gases.

This construction provides several advantages. A first advantage consists in that the heat exchanger can almost dispense with an outer insulating jacket. Furthermore the construction and manufacture of the heat exchanger are much simpler than is the case with the known heat exchanger of this type, for as the heat exchanging part proper and for the supply and discharge ducts for the media use is made of a number of identical plates which by their shapes and mutual disposition constitute not only the heat exchanging ducts but also the supply and discharge ducts for the media. In largescale manufacture of identical heat exchangers use can be made of sheet material which is cut to the same sizes and subjected to a bending operation such that the resulting plates are given the required shape. Then the bent plates are mounted in an assembling jig and connected to one another at the required points, for example by spot welding or soldering. Although the projections with which in a preferred form of the heat exchanger in accordance with the invention the plates are provided and which serve to space the plates apart by the required distances, can be provided by welding or soldering, in another form of the invention these projections are preferably shaped as ribs which extend at least substantially at right angles to the direction of length of the supply and discharge ducts for the medium and which can be formed in the sheet material by rolling during the abovementioned bending operation.

If in a further embodiment of the heat exchanger in accordance with the invention the central part of each plate extends substantially tangentially in a cross section of the heat exchanger, the advantage is obtained that the ducts in which the media are in heat exchanging contact with one another, can be made much longer than if the central parts extend substantially radially. In addition, plates comprising substantially tangentially extending parts have the important advantage that, Without the plates having to be provided with comparatively complicated longitudinal profiles, a heat exchanger made up from such plates has the property that its inner circumference is comparatively flexible with respect to the outer circumference so that through a comparatively small radial distance temperature differences of a few hundreds of degrees Centigrade can occur without giving rise, in the operation of the heat exchanger, to impermissible thermal stresses in the material.

If, in a further embodiment of the invention, in which the central parts of all the plates likewise extend substantially tangentially, these parts are shaped according to an Archimedes spiral, the advantage is obtained that the cross-sectional area of each duct formed by the plates is substantially constant throughout its length.

Hereinbefore it was described that at the inner and outer circumferences of the heat exchanger, owing to the provision of the portions and edges of the plates, ducts are produced which serve as supply and discharge ducts for the media. As a rule, the heat exchanger will be used so that the supply and the discharge of each of the media to and from each of these ducts takes place at different end faces of the heat exchanger. This may involve that both at the inner and at the outer circumference of the heat exchanger at both end faces the orifices of the ducts must be opened and closed in cyclic sequence. In one form of the heat exchanger in accord; ance with the invention this is ensured in that each end face of the heat exchanger is proided with at least one substantially flat ring which at the points of the orifices of the ducts which must be kept opened or closed, are provided with slots and partitions. respectively. Such rings can be simply made from sheet metal by punching.

In another embodiment of the heat exchanger in accordance with the invention the end in view is reached by a divergence and convergence of the fold zones and fold lines in the plates between the central part of each plate and the adjoin ng portion and/or edge such that the ducts at the inner and/or outer circumfer aces of the heat exchanger are alternately closed at either end face of the heat exchanger.

The heat exchanger in accordance with the invention is particularly suited for use in combination with a hot-gas reciprocating engine. The term hot-gas reciprocating engine is to be understood to mean an engine in a closed space of which a medium with constant phase is alternately compressed and enabled to expand by the movement of the pistons. This compression and expansion take place at different temperatures. if the hot-gas reciprocating engine is a hot-gas motor, the compression takes place at the lowest temperature and the expansion at the highest temperature, the engine being provided with a source of heat for supplying thermal energy to the medium at a comparatively high temperature. This heat source can be arranged in a combustion chamber, the heat exchanger in accordance with the invention being advantageously used as a combustion air preheater in which the exhaust gases heat the combustion air supplied to the burner. When so used the heat exchanger in accordance with the invention is particularly advantageous since it is capable of expanding at the inner circumference while the outer circumference substantially retains its initial diameter in spite of the large temperature differences between the inner and outer circumferences of the heat exchanger. Furthermore the outer circumference of the heat exchanger need not be surrounded by an insulating jacket. In the known constructions this jacket frequently has an outer diameter of such size that the distance by which other machines or engines must be spaced apart from the engine with which the heat exchanger is associated, is determined by this outer diameter and not by the greatest transverse dimension of said associated engine. In a hotgas reciprocating engine equipped with a heat exchanger in accordance with the invention, the outer diameter of the latter is not of importance.

In order that the invention may readily be carried out, examples thereof will now be described with reference to the accompanying draw ngs, in which:

FIG. 1 shows diagrammatically a cross sectional view of a heat exchanger in accordance with the invention which encloses a combustion chamber for heating the head or" a hot-gas motor, the cross sections of the separate plates being omitted for the sake of simplicity;

FIG. 2 is a plan view of this heat exchanger in which three plates are shown;

FIG. 3 is a perspective view on an enlarged scale of the ends of the central part of three adjacent plates as used in the heat exchanger in accordance with the invention and their transition to the associated portions and edge parts, and also the relative disposition of the plates;

FIG. 4 is a perspective View of a slightly modified profile for the plate used in the heat exchanger in accordance with the invention, and

FIG. 5 is a view of the inside of a modified embodiment of the heat exchanger in accordance with the invention in which the fold lines between the central parts, the bent portions and edge parts converge, the edge parts being omitted.

In FIG. 1, reference numeral 1 denotes the head of a hot-gas reciprocating engine enclosing the so-called hot space 1a. The volume of this space is periodically changed due to the movement of a piston-shaped body 2 which acts as a displacer. The upper wall or" this head it shows a number of apertures 3 arranged on a circle or circles, one leg of a substantially hairpin-shaped heating tube 4 being connected to each aperture. The other end of each heating tube extends along the side surface of the head 1 and is connected to an annular regenerator 5 encircling the heater head 1. For the sake of clearness only two heating tubes 4 with the associated apertures in the head are shown.

The medium of the hot-gas reciprocating engine which must be heated, flows through the heating tubes 4. As will be seen from FIG. 1, the heating tubes 4 surround a substantially cylindrical space 6 which is the combustion chamber of the reciprocating engine. At the upper end 7 of this chamber provision is made of a number of turbulence chamber burners 8 which direct their flames 9 to the center of the combustion chamber. Through a pipe 10 liquid fuel is supplied to the device and subsequently broken up into a fine mist in an atom zer 11 by means of a medium under pressure which is supplied through a pipe 12. The atomized fuel is supplied to a space 13, which is closed at'the upper side by a domed body 14 and is bounded at the lower side by the upper surface 7 of the combustion chamber, and mixed in this space with the primary combustion air indicated by the arrows 1. Through slits 11b formed in a sleeve 11a this air can enter the space 13. Then the fuel is mixed in the turbulence chamber burners 8 with secondary combustion air indicated by the arrows I1 and produces the flames required to heat the medium. The ignition device is not shown.

The circle of heating tubes 4 is surrounded at the outside by a heat exchanger 15 in accordance with the invention. In the embodiment shown, this heat exchanger is supported by an annular body 16 made of refractory material and in turn supports the domed body 14 which is made of refractory material.

A construction of this heat exchanger will now be described more full v'ith reference to FIGURES 2 and 3.

In 2, reference numeral 1'? denotes the space within the heat exchanger which, in the application shown in PEG. 1, is the combustion chamber. The inner and outer circumferences of the heat exchanger are designated 13 and 19 respectively. As will be seen from FIG. 2, the cylindrical part of this -reat exchanger is built up of a number of plates three of which are shown in FIG. 2 in full length from the inner surface 13 to the outer surface in FIG. 3 those parts of the same plates 2% and 22 which lie close to the inner circumference 18 of the heat exchanger, are shown on an enlarged scale and in a perspective view. Each plate comprises a central part 25W, 21 and 22 respectively, which here extends substa ti ly tangentially and is she; ed according to a Archimedes spiral. By way of fold lines 2& 21 and 22* these central parts run into portions 2%, 21 and 22, respectively. Through told lines 2%, 21 and 22 which extend parallel to one another and also to the abovementioned sets of fold lines 24?, 21 and 223, fnese latter portions terminate in edge parts Ell 21 and 2.2 respectively, which extend according to the inner circumference ltd or" the heat exchanger. As can be seen particularly from FIG. 3, the central parts of the plates are provided with ribs 2 3 formed by rolling, which n; the embodiment shown in FIG. 3 protrude to the rear through a distance which determies the relative spacing a of the plates. Owing to the provision of these ribs between each pair of plates a plurality of parallel-connected ducts are produced which each have a width as and a height h and are intended for conveying the two media which are to be brought in heat exchanging contact. Similarly to the construction at the inner circumference 18 of the heat exchanger the plates are provided near the outer circumference 19 with portions 29+, 2? and 22 which through fold lines end in edge parts 29 21 and 22 respectively which coincide with the outer circumference 1% of the heat exchanger.

When these plates, which are arranged in the correct relative positions, for example, in an assembling jig, are connected to each other, for example by soldering or welding, at the two end faces 2 and 25 of the resulting body (FIG. 1), a body is produced which has a great strength and nevertheless, owing to the tangential arrangement or" the central parts of each plate, is so flexible at its inner side that this side is capable of expanding relatively to the outer side.

The spaces provided between the portions, the edge parts and the adjacent central parts of adjoining plates, which spaces are designated 26, 27, 28 and 29 in FIGS. 2 and 3, can be used as supply and discharge ducts for the media to be brought into heat exchanging contact. In order to ensure a highly intimate contact between the media passing in counterfiow through the heat exchanger, these ducts alternately convey different media. Thus in the embodiment shown in FIGS. 2 and 3 the space 26 at the lower end or" the heat exchanger will be fed with hot combustion gases. These pass through the heat exchanger from its inner circumference 1% towards its outer circumference 19. They leave the heat exchanger at the upper end though a duct Ed and are discharged through a chimney 313 (FIG. 1). The combustion air to be preheated is admitted at the low r end of the heat exchanger into the space 29, flows through the heat exchanger from the outside to the inside and leaves it at its upper end through the space 2.7. Here this preheated combustion air is divided in the above-mentioned air stream I which serves as the primary combustion air and in a stream Ii which acts as the secondary combustion air.

For closing the spaces alternately at the upper and lower sides use is made of fiat metal rings designated 31 in FIG. 1. These rings have alternate partitions and apertures and can be secured to the heat exchanger by not removing the ring portions which must form apertures but bending them through 90 from the plane of the rings and introducing them in the upper and lower sides respectively of the spaces 50 that the rings are firmly secured.

Obviously the plates may be formed in shapes different from those shown in FIGS. 2 and 3. As is shown in FIG. 4, the central parts 32 and 33 of plates 32 and 33 may extend about similarly to the corresponding parts shown in FIGS. 2 and 3, the transitions to portions 32 and 33 and to edge parts 32 and 33 being smoother. Alternatively the central parts of the plates can be caused to extend more radially, which generally will result into the heat exchanging ducts being shortened.

As is shown in FIG. 5 with respect to a heat exchanger of slight height, fold lines 34 and 35 may alternatively converge or diverge so that at the inner and outer circumferences spaces 36 and 37 formed between the bent portions and the edge parts are already closed by the relative arrangement of these fold lines.

What is claimed is:

1. A cylindrical heat exchanger comprising an annular chamber, a plurality of concentric, slightly resilient metal plates in said chamber, each having a curved central portion, an end part bent at an angle to said central portion and an extremity conforming in shape to one of the walls of said heat exchanger and abutting therewith, said metal plates forming at the end parts and extremities thereof a multiplicity of closed, adjacent supply and discharge ducts for the media traversing the heat exchanger, the media in the curved central portions of said heat exchanger being in heat exchanging relationship, and said extremities of the concentric metal plates being secured together, the relatively cold combustion air being supplied to certain predetermined ducts of said heat ducts of said heat exchanger, said air leaving the heat exchanger through other predetermined ducts located at the inner surface of said heat exchanger.

2. A cylindrical heat exchanger as claimed in claim 1 wherein said central portions of the concentric metal plates extend substantially tangential to said annular chamber.

3. A cylindrical heat exchanger as claimed in claim 2 wherein said central portions of the concentric metal plates are in spiral configuration.

4. A cylindrical heat exchanger comprising an annular chamber, a plurality of concentric slightly resilient metal plates in said chamber, each having a curved central portion, an end part bent at an angle to said central portion and an extremely conforming in shape to one of the walls of said heat exchanger and abutting therewith, said metal plates forming at the end parts and extremities thereof a multiplicity of closed, adjacent supply and discharge ducts for the media traversing the heat exchanger, the media in the curved central portions of said heat exchanger being in heat exchanging relationship, and said extremities of the concentric metal plates being secured together, the relatively cold combustion air being supplied to certain predetermined ducts of said heat exchanger, said air leaving the heat exchanger through other predetermined ducts located at the inner surface of said heat exchanger, a plurality of ribs formed on said plates extending substantially perpendicular to the longitudinal axis of said supply and discharge ducts.

5. A cylindrical heat exchanger as claimed in claim 1 wherein the fold lines in said metal plates between the curved central section and the adjacent end part bent at an angle commences alternate diverging and converging portions, each resulting in ducts.

References Cited in the file of this patent UNITED STATES PATENTS 2,059,114 Karmazin Oct. 27, 1936 2,369,993 Turner Feb. 20, 1945 2,557,607 Lubbock et al June 19, 1951 FOREEGN PATENTS 162,250 Great Britain July 21, 1922 

